Virtual golf systems are widely spreading which allow golfers to virtually play golf at low cost in downtown areas and the like. The basic concept of such virtual golf systems is to acquire a number of photographed images of a golf ball upon being hit by a golfer, measure physical quantities of the golf ball on the basis of the trajectory, interval, size and the like thereof, perform a simulation of the shot, and display a result of the simulation on a screen. In some cases, it may be much required in the virtual golf systems to acquire a projection image of an actual movement trajectory of a moving golf ball on the basis of the photographed images of the golf ball.
Therefore, following the introduction of a remarkable virtual golf system in Korean Patent No. 1048864 (entitled, “METHOD OF MEASURING PHYSICAL QUANTITIES OF OBJECT BY USING SINGLE LIGHT SOURCE AND PLANAR SENSOR UNIT AND VIRTUAL GOLF SYSTEM UTILIZING SAME”) (the contents of which are incorporated herein by reference in its entirety), the inventor(s) now present a novel technique to combine with such virtual golf systems, other virtual golf systems, systems for virtually playing other kinds of sports (e.g., baseball, football, etc.), virtual reality systems for subjects other than balls, or the like to enable them to produce sufficiently good simulation results just using some economical components.